Torrefied Oak Try Square


During one of my visits with Jim Tolpin a couple weeks ago, a student delivered a small board of torrefied maple to Jim for experimentation. Torrefaction is a process in which wood is heated beyond the combustion point in an anoxic environment (so that it doesn’t actually burn). This process is like an accelerated aging process by removing the volatiles that usually take many years to oxidize and mineralize. The natural mineralization of the volatiles inside the wood makes it so that so that moisture does not pass through as readily. This is the reason antique lumber is more dimensionally stable then new wood – it’s pores are clogged. Today, torrefaction is being used to reproduce this natural aging process for several applications – the flooring industry and guitar making, especially. Maine-based guitar maker, Dana Bourgeois, has been torrefying his guitar tops for over 20 years and has become a go-to expert on the process. This has lead the way for many other big-name guitar companies to follow suit. The other fascinating thing about torrefied wood is that is turns the wood quite dark. The oak I was gifted from Brendan Gaffney is black and resembles bog oak.

The reason Jim Tolpin was given torrefied wood was because he was interested to see how it behaves as a try square. He and I wondered if the stability overshadows the brittleness of the final product. To find out, today I finished a large try square with the oak I got from Gaffney. I wanted a large square for dealing with these 18”-wide boards in the shop build.

After working with the stuff, here are my thoughts…

  1. It’s beautiful. I’ve always loved the look of bog oak and this is very close.
  2. It’s brittle. Especially because oak is already prone to chipping, getting crisp edges requires more care and attention. (See ends of tenons in last image.)
  3. Planing it is strange. Instead of long shavings, the wood turns into tiny curls under a plane iron. It’s weird.

Bottom line: Is it necessary to use specially treated wood for stabilization? No. I don’t have any problems with the stability of my cherry and maple squares. So, besides raw curiosity, I really just love the color.

The square is complete with the exception of a few pins in the tenons for a mechanical lock. Also, I haven’t yet decided if I wanted to shape the end of the blade yet. I’ve laid out a few ideas but nothing has jumped out at me. I might just leave it square.

- Joshua